The ideal method for non-invasive monitoring of biological or metabolic activity in the brainstem has not yet been established. Existing methods for evaluating cerebral tissue (e.g. PET) have limitations when applied to the brainstem. New noninvasive imaging methods are currently being studied. We are using MR perfusion, DEMRI, NMRS and PET to further investigate the imaging characteristics of pontine gliomas over time after radiation therapy.